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So after making the freakin’ small 50MHz transverter, now I made a second VFO for my FT901DM transceiver.
Actually it is not anymore FT901DM because it lacks some things:
- lamps :-), replaced by a push pull transistorised amp.
- High voltage transformer, replaced by a 12V connector
- 25kg weight replaced with 5kg
- lot of iron replaced by alluminium, of course
- lot of current draw for nothing
- the memory unit – replaced now by the second VFO
- the nonexisting transverter I/O -replaced already in 2010 with one :-)
The second VFO has three transistors, and 7 varicaps: 6 (3+3 back to back or front to front or whateve’)
for tuning and one for fine tuning or RIT. Drift free and Hartley design with FET oscillator.
Yesterday I made a noise blanker. The only one I’ve made.
You may find that very few homebrew transceiver designs have this option, an option that may be of much more importance than the AGC for example.
My NB PCB is about 30×20 mm (click to enlarge)
From my new location, where I use just a vertical “balcony” antenna at the moment, I was very surprised of the amount of noise (just above 59!!! on my S’Meter) on 28, 50 or 144MHz that apears every day, at random hours, without regard of season. I never realised that I could get rid of this electrical noise that mask completely even very good CW or SSB signals.
And another picture, the noise blanker and the PCB for a little varicap controlled VFO that I’ve “painted” also yesterday (click to enlarge)
At least! The Mizuho style noise blanker did it! Only three transistors some fast Schottky or Germanium small signal diodes in this simple and efficient design!
And it is driven with 10,7MHz IF (in Yaesu designs, you need another two stages: a mixer and a local oscillator for converting the IF to 455KHz).
(click to enlarge)
I just made the first QSO with my new transverter that I designed and made in only 3 days. The test QSO was made with my friend Stefan – YO5PBW located about 5 km away but in the same city. It has excellent sensitivity and very low noise. I was using only 2W because I was using just a small heatsink for the 2SC1971 VHF power transistor as you can see in the picture below. I must tweak the PA stage a little bit prior to put this TSVR into the aluminium case. I’m very happy for my simple but just the best possible :-) design. This remainds me about YO2IS who brought the “K.I.S.S.” acronym into my atention.
Definitely YES: KEEP IT STUPID SIMPLE!
Yesterday I made the schematic and also the PCB of my newest radio “thing”: hope — the smallest home made transverter for 6m (50MHz). It is about 10×10 cm and until now I already finished the RX/LO/BPF part. It has ultra-low noise, no mechanic relay, good sensitivity. Only classic components, no SMD!
For the transmitter part I expect 4 to 7 watts effective power. As soon as finish it i’ll post pictures.
It can work with 14 or 28 MHz transceiver (or other bands, but i only have crystals for these two).
I would really like to make a business from very little transverters and transceivers called microR… or something.
Now, i must put a page with beautiful links that I visit. Thats because i sometimens forget to save them and these are sometimes links that i harly find. I have about 300 tabs at every start of my Firefox blrowser… I just pray not to disapear in a crash.
These beatiful guys (Oscar the cat and Esky the husky dog) still dream about me. I was the carefull mother for them. Unfortunately they wanted to eat my thounsand cables, my homebrew transceivers and not the artificial food, but only the one I eat with the courtesy of my mother :-). I miss them so much!
Y Oscar 5PBG, the cat:
Esky, my dear little beast
This view is in front of my window. And this tower about 20m high would be excelent for some VHF antennas. Ok, I have other towers in front, 10km away you can se those 1.3 km ASL ones. Just good for contesting with quite low power.
Winter version:Summer Version: